Weird tone control issue

[sonofmickel]

I am building a JCM800 circuit in a donor amp. I am wiring the tone stack exactly like a JCM800 or Plexi(identical cathode follower circuits). Anyway the Treble is acting like a volume control. At full OFF the volume is loudest, as the treble is rotated towards "10" the volume cuts drastically and the mids also get cut by a large amount. I have swapped parts and rebuilt the circuit no less than 5 times.

Has anyone had this problem before? I can't figure it out and I am losing my mind!

[neikeel]

I can imagine that you have wired the treble in as a the MV (on a plexi the MV is wired just before the PI coupling cap

Post a couple of clear photographs (or links to them) of the area from a couple of amgles in good light.

[sonofmickel]

I wish it were that simple.
Here is a pic, excuse the "mess" I am just trying to figure out this wanky tone stack. The yellow clip is the signal feed from the cathode follower. The .022 feeds the effects loop, then to a 12ax7 recovery stage , then to the PI.

[stef]

Is this the 2210 circuit?

[sonofmickel]

Not a 2210, this is the tonestack from a standard Plexi or JCM800 except this one goes from left to right: Treble, Bass, Mid, Volume.

[stef]

2210 is a JCM800 series model just like 2203/4/5/bass models etc. There are many "plexi" models/ specs too...
I suggest you to visit this site and study and strictly follow layouts and schematics and you will eventually resolve the issue
http://home.comcast.net/~mamp17/index.html

[sonofmickel]

Awesome. Thanks for the links, treasure!
Larry helped me out on the tone stack. Turns out that the Volume control was a 25k, that makes the tone stack act like a full boost or extreme high pass filter. Whoda thunk?
Learning stuff new every day. Thanks for all the help people.